Plunger



Mardi y BEEH v2,438,839

` PLUNGER Filed July 16, 1945 F/G. 2. F/G. 3.

BY Ma fm ATTORNEY.

Patented Mar. 30, 1948 PLUNGER lLouis. Beeh, Long Meadow, Mass., assignor to Bulova WatchrCompany, lncifNew York, N. Y., Y v a corporation of New York f, application July 1e, i945, serial No. 605,405

(ci. acs-2c) i 2 Claims.

y The invention relates to a plunger and rod connection. In certain types of pumps such as for instance fuel pumps lwhere the pumped uid can be characterized as a Ygrease or oil remover, the

danger exists of the plunger freezing in the pumpA cylinder during the operation and that, in consequence, a break of the one or other of the driving elements occurs, If such break takes Aplace in a multiple pump the entire machine usually is put out of operation althoughthe original daim age may affect only one oi a larger number oi pump units actuated by `a commondrive.

The invention aims to minimize `the injury caused for instance by a freezing plunger, :and it essentially consists in the provision of means whereby any break due to anlexcessive strain of the connection of the plunger and its connecting rod will occur in a predetermined element or part of the connection, so selected that an inexpensive and easy replacement is possible. ject of the invention isthe vprovision olf :a space 'in the plunger for a free movement of the connecting rod if the connection of the parts is broken.

Further objects and details of the invention will be apparent from the description given hereinafter and the accompanying -drawing illustrating several embodiments thereof by way of example. In the drawing, Figs. 1, 2 and 3 :are cross sections of three different plungers and rod connections according to the invention. Referring to the drawing the plunger I of Fig. 1 i-s a hollow cylindrical body 2 with a bottom 3 at one of its ends. Body 2 has an inner shoulder Il and on that shoulder an element 5 is seated with a relatively thin flange-like projection 6 which is an integral portion of said element, The latter is provided with a semi-spherical cavity 1 in which the ball head 8 of the connection rod 9 engages. Shoulder 4'. is at such a distance from th'e plunger bottom 3 and element 5 is so shaped that between the two there is a free space I of an axial length not less than the length of the stroke intended to be performed by the plunger. The stroke may be derived from any suitable drive. A wobble plate -drive for this purpose is indicated in dash' lines. The wobble plate I encompasses the upper ball head I8 of the connecting rod 9 and is non-rotatably'held by means not shown. A drive shaft 52 turning about its axis a has a cylindrical end portion 53 inclined with respect to the axis a and journaled in the wobble plate 5I. Thus, if shaft 52 rotates th'e wobble plate will be reciprocated with the center of the ball head I8 moving between the end positions b and c. The distance Another ob v b-c is equal to the aforementioned intended stroke of the plunger. A slotted washer II is positioned in the rear of the ball head 8' and may have, for this purpose, a spherical surface |2`in a middle portion I3 which may be thicker than the peripheral zone ofthe washer,` A tubular part Ill having an outer Vthreading l5 and an outwardly projecting flange `I6 isinserted into the plunger from its open end and screwed into an interior threading -I1 of the latter. Flan-ge lbears on the top rim of the body 2 and simultaneously on the washer II so that the head 8 of the connecting rod is held between the parts 5 andV Il. The thicknesses of both the flange'i and th'e washer I I are soselected with respectto the strength of the other parts of the rod connection fand the drive (not shown) that a break of either the ilange or the washer or both will occur if the load, i. e. pressure transmitted by the'connecting rod, exceeds a predetermined value. With plungers of the illustrated form, movement in the direction of the bottom will take place during the compression stroke, and movement in the opposite direction during the suction stroke. Thus, if an overload occurs, for instance due to freezing of the plunger, at the beginning of the compression, flange 6 will break and the rod 9 will push th'e remainder of the element towards the bottom 3. As the space I!) is of a length, as stated hereinbefore, not less than that of the stroke, no other part or portion will be damaged Should the freezing' of the plunger occur during compression between the dead centers, rst the flan-ge 6 will break an-d then washer II whereas the sequence of breaks will be reversed when the plunger freezes during the suction stroke. In no event, however, any :additional damage will occur, and if the plunger is one of a number of similar ones operated by a common drive, only the one unit will become inoperative while the others continue to work.

'I'he plunger according to Fig. 2 has a body 20 with bottom 2|, shoulder 22 and interior threading 23 in an arrangement similar to that of the corresponding parts of Fig. 1. An element 245 bearing with a thin flange 25 on shoulder 22 forms the seat 26 for the ball hea-d 21 of the connecting rod 28. The head is held on its seat by an integral rim 29 of the element 24, the rim being turned down on the ball head 21 after its insertion in the seat-forming cavity 26. Again, the space 30 between the plunger bottom 2| and the element 24 is at least according to the length of the plunger stroke, and flange 25 is. so thin that it will break under an excessive load. The

liange is held against its seat by the tubular member 3| which is pressed down by an externally threaded piece 32 screwed into the inner thread 23 of the body. In order to facilitate a break at the predetermined location, the tubular member which for that purpose may be of steel or similar hard material, is provided with a circular cutting edge 33. This edge will be capable of shearing off the flange 25 so that the element 24 can freely move in space 30 when an overload with resulting break occurs. Of course, it is also .possible so to select the strength of the rim 29 that the latter may open and permit the head 21 to slip through. However, this is less desirable as in such an event, upon the return stroke of the connecting rod, a hammering or impact action must be expected which may cause injury to the connecting rod proper or other parts of th'e drive.

Whereas in Fig. 2 only one cutting edge has been provided which can be effective only during plunger movement in one direction, there are two such edges in the embodiment of Fig. 3 in orderY to obtain, if necessary, a shearing action during either stroke. In Fig. 3, the plunger body 40 has an inner cylindrical surface 4| of constant ydiameter except for the inner threading 42 of the top end. A first tubular member 43 is iitted into the cylinder 40 and bears upon the top surface 44 of the plunger bottom 45. Tube 43 has an upper cutting edge 46 and is of such length that there is the required distance between the surface 44 and an element 41 which sits with its flange 48 on that edge and is similar to the element 24 of Fig. 2. A second tubular member 40 with a lower cutting edge 50 is screwed into the threading 42 so that ange 48 is placed between the edges 46 and 50. In consequence, a shearing effect can take place for either direction of plunger movement. y

Although I have shown only three embodiments of my invention it will be apparent to those skilled in the art that many alterations and modications are possible without departure from the essence and spirit of the invention which, for this reason, shall not be limited but by the Yscope of the appended claims.

I claim:

1. A plunger and connecting rod assembly for a multiple injection pump or the like comprising a hollow cylindrical plunger body closed on one of its ends and having an inner shoulder, .a ball headed connecting rod, a hollow, spherical bearing member tting said connecting rod, and including an outer flange, a tubular member iitting the inner wall of said body and extending between the other end of said body and said/flange and constituting a means to hold said ange bearing against said shoulder, said flange being so dimensioned as to break when said connecting rod causes on said member a load substantially exceeding the maximum pressure in normal operation, and said plunger forming between said Closed end and said shoulder a chamber of a length at least equal to the intended plunger stroke and Vof suiiicient width to permit the connecting rod when a break of said ange occurs, to reciprocate said member in said chamber,

2. A plunger as claimed in claim 1 said tubular member having a shearing edge bearing on said ange.

LOUIS VBEEH.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS 

